GLACIERS OF UNAKWTK INLET AND COLLEGE FIORD 293
that spruce extends up to the lips of several hanging valleys on the west side of the fiord shows that ice tongues have not extended out of these valleys for a century or more. Absence of spruce on spurs between hanging valleys may be attributed to snowslides. Ranney Glacier has evidently been retreating for several years because there is a large barren zone in front of it, marking the distance to which the glacier had advanced during the last maximum. Mature alders extend up to t-hiq barren zone.
Pedro Glacier heads in snowfields south of Brilliant Glacier terminating 3% miles east of Unakwik Inlet and sending a small stream through two lakes to the cove of Miner's River. Muth Glacier, and three small ice tongues in an enormous cirque at the base of Unakwik Peak, terminate 1$ to 2J miles west of the heads of Jonah and Siwash Bays respectively.
Glacial Modifications of the Fiord. Throughout Unakwik Inlet there is evidence of profound glacial erosion at a time when the Meares Glacier was much larger, receiving Ranney, Brilliant, Pedro and many small ice tongues as tributaries, and occupying all of Unakwik Inlet, forming one of the great tributaries of the piedmont glacier of Prince William Sound. There is also evidence of local erosion by the former tributaries of the Unakwik Inlet Glacier; for example, in the enormous cirque east of Unakwik Peak which has been cut back so far as to form a narrow arrSte between Unakwik Inlet and College Fiord on which Unakwik Peak is the highest point. A J/W*SH B*V similar narrow arre'te has been developed between Meares and Brilliant Glaciers.
The main channel of Unakwik Inlet j^ SQ NATURAL SCALE CBOSS-SBCTION or has the typical fiord topography, that INUDT.
is, it is straight and simple and has no Submerged hanging valley of Siwash Bay.
spurs entering from either side, as a
stream-eroded valley does. Instead, the spurs are all cut off with triangular facets and the fiord walls are eroded smoothly, although the width of the fiord varies from place to place. At the point where it is narrowest, in the turn west of Meares Glacier, one wall of the fiord is very much steeper than the other. As might be expected, the west Wall is the steeper, this being the side on which the ice must have eroded most efficiently while the glacier was making this abrupt turn. The spur east of this curve slopes more gradually.
The tributary valleys that enter the inlet bear various relationships to the present water level in the fiord. Some of them enter at or just below sea level, — for example, Miner's River. Others end in the air and have streams which cascade down from the lips of hanging valleys (h, Fig. 88). Ranney Glacier is in such a hanging valley, and there are several others south of it on the west side of the fiord, some of them with a discordance of several hundred feet. There are also two hanging valleys on the east of the fiord. Still other tributary valleys are occupied by bays and it was not known that these were hanging valleys until soundings were made in 1910. These soundings show conclusively that the hanging relationship exists in Siwash Bay (Fig. 39), which hangs 790 feet above the bottom of the Unakwik Inlet. Although soundings were not made in Jonah Bay, it presumably has the same relationship. The channel behind the long island just south of Miner's River, with a depth of 126 feet, and the channel between the mainland and Olsen Island, at the south end of Unakwik